1,455 research outputs found
Multi-wavelength visibility measurements of the red giant R Doradus
We present visibility measurements of the nearby Mira-like star R Doradus
taken over a wide range of wavelengths (650--990 nm). The observations were
made using MAPPIT (Masked APerture-Plane Interference Telescope), an
interferometer operating at the 3.9-m Anglo-Australian Telescope. We used a
slit to mask the telescope aperture and prism to disperse the interference
pattern in wavelength. We observed in R Dor strong decreases in visibility
within the TiO absorption bands. The results are in general agreement with
theory but differ in detail, suggesting that further work is needed to refine
the theoretical models.Comment: 8 pages; SPIE Conf. 4006 "Interferometry in Optical Astronomy
Flatness optimization of micro-injection moulded parts: The case of a PMMA microfluidic component
Micro-injection moulding (µ-IM) has attracted a lot of interest because of its potential for the production of low-cost, miniaturized parts in high-volume. Applications of this technology are, amongst others, microfluidic components for lab-on-a-chip devices and micro-optical components. In both cases, the control of the part flatness is a key aspect to maintaining the component's functionality. The objective of this work is to determine the factors affecting the flatness of a polymer part manufactured by µ-IM and to control the manufacturing process with the aim of minimizing the in-process part deformation. As a case study, a PMMA microfluidic substrate with overall dimensions of 10 mm diameter and 1 mm thickness was investigated by designing a µ-IM experiment having flatness as the experimental response. The part flatness was measured using a micro-coordinate measuring machine. Finite elements analysis was also carried out to study the optimal ejection pin configuration. The results of this work show that the control of the µ-IM process conditions can improve the flatness of the polymer part up to about 15 µm. Part flatness as low as 4 µm can be achieved by modifying the design of the ejection system according to suggested guideline
Domino Michael-aldol annulations for the stereocontrolled synthesis of bicyclo[3.3.1]nonane and bicyclo[3.2.1]octane derivatives
Domino Michael-aldol annulation of cycloalkane-1,3-diones with enals affords a general route to 6-hydroxybicyclo[3.3.1]nonane-2,9-diones and 2-hydroxybicyclo[3.2.1]octane-6,8-diones, notably in one-pot procedures under convenient conditions. The annulation is shown to be compatible with one or more substituents at six positions of the bicyclo[3.3.1]nonane-2,9-dione scaffold. In some cases, the relative configuration of the product can be controlled by the appropriate choice of solvent, base and temperature for the annulation. In contrast to the chair–chair conformations usually adopted, the bicyclo compounds derived from 2,4,4-trimethylcyclohexane-1,3-dione possessed boat-chair conformations. Oxidation of the annulation products gave the corresponding bicyclo triketones
Design and fabrication of a three-dimensional microfluidic device for blood separation using micro-injection moulding
Micro-manufacturing is a fast developing area due to the increasing demand for components and systems of high precision
and small dimensions. A number of challenges are yet to be overcome before the full potential of such techniques is
realised. Examples of such challenges include limitations in component geometry, material selection and suitability for
mass production. Some micro-manufacturing techniques are still at early development stages, while other techniques are
at higher stage of manufacturing readiness level but require adaptation in part design or manufacturing procedure to
overcome such limitations. This article presents a case study, where the design of a micro-scale, biomedical device is
adapted for functionality and manufacturability by a high-volume micro-fabrication technique. Investigations are described
towards a disposable three-dimensional, polymer-based device for the separation of blood cells and plasma. The importance
of attempting a three-dimensional device design and fabrication route was to take advantage of the highthroughput
per unit volume that such systems can, in principle, allow. The importance of a micro-moulding fabrication
route was to allow such blood-containing devices to be cheaply manufactured for disposability. Initial device tests
showed separation efficiency up to approximately 80% with diluted blood samples. The produced prototype indicated
that the process flow was suitable for high-volume fabrication of three-dimensional microfluidics
Lidar data analyses for assessing the conservation status of the so-called baths-church in hierapolis of phrygia (TR)
The LiDAR technology has aroused considerable interest in the field of structural study of historical buildings, aimed at the structural assessment in the presence of different states of stresses and at the evaluation of the health status.
The interest is due mostly by the ability of generating models of the built structures being able to predetermine different levels of schematization, two-dimensional and three-dimensional, in order to be able to perform evaluation processes assigning simplified geometric contents that correspond to the physical reality of the artefacts.
This paper intends to report some results of these experiences applied in archaeological domain, to the so-called Baths-Church at Hierapolis in Phrygia (Pamukkale, TR). In particular, the generation of accurate models from dense clouds and their reduction to models with simplified geometries too, is explored, with the further aim of testing automated strategies for features detection and editing process that leads to appropriate models for visual and analytical structural assessment. The accuracy and density parameters of the LiDAR clouds will be analysed to derive orthophotos and continuous mesh models, both to obtain the best results from the application of research algorithms such as region growing to detect blocks, and to allow visual analysis on digital models and not on site.
The ability to determine with high accuracy both the size and the anomalies of the wall systems (out of plumb and other rotation or local mechanisms of collapse), together with the possibility of identifying the lay of the individual drywall blocks and also the signs of cracks and collapses, allow deriving suitable models both for FE (Finite Elements) analysis and DE (Discrete Elements) analysis, as well as analytical ones
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Leveraging incentives to increase HIV testing uptake among men: qualitative insights from rural Uganda.
BACKGROUND:Few studies have explored how economic incentives influence behavioral outcomes. This study aimed to identify pathways of action of an incentives-based intervention to increase men's participation in HIV testing. METHODS:The qualitative study was embedded in a randomized-controlled trial that compared effectiveness of gain-framed, loss-framed and lottery-based incentives to increase HIV testing among men. Following testing at a community health campaign, 60 in-depth interviews were conducted with men systematically sampled on the basis of age, incentive group, and campaign attendance. Data were coded deductively and inductively for thematic content analysis. RESULTS:Incentives addressed men's structural, interpersonal and individual-level barriers to testing: offered at convenient locations, incentives offset costs of testing, in lost wages, which are exacerbated when livelihoods required mobility. Interpersonal barriers included anticipated stigma/fear of disclosure, social obligations, and negative peer influences. Providing incentives in public settings provided "social proof" that prizes could be won, and facilitated social support and positive norms by promoting testing with trusted others. Incentives had little influence when men appraised prize values to be low, disbelieved they would win a prize, or were already intrinsically motivated to test. Yet, incentives provided a behavioral 'cue to action' for many men who perceived themselves to be susceptible to HIV and perceived HIV disease to be severe, acting as secondary motivator for testing that "sweetened the deal". CONCLUSION:Incentives can be an important 'lever' to promote men's healthy behaviors in resource-poor settings. HIV testing in convenient, public settings, when paired with incentives, provides multiple pathways to stimulate men's testing uptake. TRIAL REGISTRATION:Registered with ClinicalTrials.gov on 08/10/2016, ID: NCT02890459. The first participant was enrolled on 11th April 2016
Risk of recurrence after a first seizure and implications for driving: further analysis of the Multicentre study of early Epilepsy and Single Seizures
Objective To determine for how long after a first unprovoked seizure a driver must be seizure-free before the risk of recurrence in the next 12 months falls below 20%, enabling them to regain their driving licence
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